There are several methods of producing visual effects of 3D to a viewer. One of the methods is to present two sets of moving pictures separately to the viewer's left and right eyes. This is called stereoscopic imaging which involves capturing of the two sets of moving pictures using two cameras. One of the techniques used previously to present stereoscopic video is using filtering of color components where each eye can only view. Such techniques reduce the resolution of a picture that reaches each eye.
Recently, with the advancement in display technologies, viewers are now able to view full resolution video with each eye. The video standard H.264/MPEG-4 AVC Multiview Video Coding (MVC) is designed for the compression of such 3D imaging where each view is presented in the full resolution.
The video standard H.264/MPEG-4 AVC Multiview Video Coding (MVC) provides a set of compression tools which allow the efficient compression of moving pictures targeted for more than one set of views. The video standard MVC allows the compression of pictures using predictive coding from reconstructed pictures of a different set of views. This “inter-view” prediction utilizes the correlation of pictures captured by different cameras at approximately the same time to efficiently compress the pictures.
In the video standard MVC, the “inter-view” prediction is performed only on pictures of different views having the same picture order count information. The picture order count information is used to indicate the order of reconstructed pictures of the same view. In the video standard MVC, pictures (or view components as defined in the MVC standard) of different views having the same picture order count information are grouped together as a container called an access unit.
In the video standard MVC, an anchor picture is defined as a coded picture in which all slices reference only to slices within the same access unit. An anchor picture is identified by a bit carried in the NAL Unit header of the coded picture as shown in FIG. 1. More specifically, the anchor picture is identified by the bit indicated by an anchor_pic_flag parameter. Here, FIG. 1 illustrates an example of a data structure of an access unit.
This bit allows an MVC decoder to identify the anchor pictures in the coded video sequence and treat them as random access points where the MVC decoder may successfully reconstruct the pictures without decoding pictures before the anchor pictures.
As shown in FIG. 1, the access unit contains view components where only a view component of a view 1 is a base view component while the rest of the view components are non-base view components. The non-base view component that immediately follows the base view component is the first non-base view component.
The H.264/MPEG-4 AVC High Profile is widely used in various applications, such as High Definition Storage Media and High Definition Digital Video Broadcast. The Multiview High Profile defined in the video standard MVC Is designed as an extension of the H.264/MPEG-4 AVC High Profile where existing implementation of H.264/MPEG-4 AVC High Profile decoders can be easily modified to support the decoding of compressed video streams using the Multiview High Profile.
As described above, the anchor pictures can be used as random access points. Thus, the anchor pictures are essential to these applications where functionalities like trick play or stream switching are necessary.
An anchor picture is defined in the video standard MVC as a coded picture in which all slices reference only to slices within the same access unit. In the video standard MVC, an access unit consists of one or more view components depending on the number of views supported.
For most applications, to achieve better compression efficiency, only one of the view components in an anchor access unit will be Intra coded and the rest of the view components within the same anchor access unit will be Inter coded. The Inter coded view components utilize inter-view prediction from the Intra coded view components. An Intra coded view component utilizes only spatial prediction tools (e.g. Intra Prediction) for the reconstruction of the view.
In video standard like H.264/MPEG-4 AVC or MVC, reference picture lists are used to identify the reference pictures that can be used for the prediction of samples for each image. When each coded block of a coded picture is decoded, a reference picture for prediction can be referred to by signaling an index to the reference picture list (see PTL 1).
An initialized process is defined in MVC for the creation of these lists for both inter prediction and inter-view prediction of samples for each view component. As defined in the video standard MVC, the initialized process of the reference list will place the reference pictures belonging to the same view at the beginning of the list and the inter-view reference pictures at the end of the list. An example of such a reference picture list is shown in FIG. 2. Here, FIG. 2 illustrates an example of the initialized process of the conventional reference picture list.
As described above, the predictive coding can be performed using the reference picture list indicating intra-view reference pictures (inter prediction) and inter-view reference pictures.